Use a bitfield to store animatable properties.

ui/compositor/scoped_layer_animation_settings.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/compositor/scoped_layer_animation_settings.h"
 
 #include "ui/compositor/layer.h"
 #include "ui/compositor/layer_animation_observer.h"
 #include "ui/compositor/layer_animation_sequence.h"
 #include "ui/compositor/layer_animator.h"
@@ skipping 43 matching lines @@
     }
   private:
     scoped_ptr<LayerAnimationElement> GetInverseElement(
         LayerAnimationSequence* sequence,
         gfx::Transform base) const {
       const size_t expected_size = 1;
       DCHECK_EQ(expected_size, sequence->size()) <<
         "Inverse supported only for single element sequences.";
 
       LayerAnimationElement* element = sequence->FirstElement();
-      LayerAnimationElement::AnimatableProperties transform_property;
-      transform_property.insert(LayerAnimationElement::TRANSFORM);
-      DCHECK(transform_property == element->properties())
+      DCHECK(LayerAnimationElement::TRANSFORM == element->properties())

[sky, 2014/01/13 14:26:42]

DCHECK_EQ

[Ian Vollick, 2014/01/13 19:03:59]

Done.

         << "Only transform animations are currently invertible.";
 
       scoped_ptr<LayerAnimationElement> to_return(
           LayerAnimationElement::CreateInverseTransformElement(base, element));
       return to_return.Pass();
     }
 
     Layer* base_layer_;
     // child layers
     std::vector<Layer*> inverse_layers_;
@@ skipping 77 matching lines @@
   }
   inverse_observer_->SetLayer(base);
 }
 
 void ScopedLayerAnimationSettings::AddInverselyAnimatedLayer(
     Layer* inverse_layer) {
   inverse_observer_->AddInverselyAnimatedLayer(inverse_layer);
 }
 
 }  // namespace ui